I find that very strange. I live near central london which obviously has very good 'normal' coverage but they didn't put up a fight at all.
I also did have problems with billing. Unlike you they totally failed to set up a DD after I changed bank accounts so I was stung with month after month of £5 'payment method charges'.
Emailing
[email protected] or w/e it is has sorted all my problems out though with them. They refunded all my payment method charges, set the DD up and gave me a free month's service as soon as I emailed them.
To be fair to three though I didn't have to contact them to get the homesignal. The guys were good, maybe the policy has changed on them?